Aid me to take a laptop

Hello!

I'm seeming for a laptop.I'm not actually adjust with a brand, but here is what I was wishingfor:

Less than $600 , Smaller than 15-inches , More than 3+hours of battery life , 3-4gb of RAM
minimum of 160 GB Hard Drive, Decent Graphics ,Windows 7 Something at least fairly sleek seeming,I've searched and tried, but I get so bogged down. Is ASUS good?Should I just stick with HP ? How about the ACER matter? Dell?